It's likely that your house battery solenoid went south. That little "pinging" noise at switch activation comes from your propane detector. At any rate, look under your entry steps at the battery storage area. Somewhere on the wall or near that battery tray is your solenoid. Take a good look at the cable & wire connections to make sure they're snug & corrosion free. On each side of the solenoid you should see little blade fuses; pull them out and test them (don't trust holding them up to the light to see if they "look good"...
IMHO, I think your problem is either bad house switch or a bad solenoid. Activate your house switch briskly for about eight or ten times; -maybe the contacts are going bad. When you activate the house switch you should hear the solenoid click. Better yet, have the DW activate the rocker switch and you hold the solenoid; -you should feel it "click" in your hand.
If replacing the solenoid, go to an RV store; this is a constant duty solenoid and a lot of the automobile parts stores offer replacements that are not constant duty.
Lastly, you can do an "advanced search" in these forums; there's lot of good info in these pages.